为什么HTTP POST返回代码400（错误的请求）？ HTTP POST方法 [英] Why HTTP POST returns code 400 (bad request)? HTTP POST Method

问题描述

为什么服务器返回响应代码400（坏请求）？ （不起作用）

  URL serverAddress = new URL（uri）; 
 HttpURLConnection连接=（HttpURLConnection）serverAddress.openConnection（）; 
 connection.setDoOutput（true）; 
 connection.setDoInput（true）; 
 connection.setRequestProperty（Content-Type，contentType）; 
 connection.setRequestMethod（POST）; 
 int status = connection.getResponseCode（）; //返回400 
  

例如，这个HTTP GET返回代码200：（works）

  / **创建连接** / 
 URL serverAddress = new URL（uri）; 
 HttpURLConnection连接=（HttpURLConnection）serverAddress.openConnection（）; 
 connection.setRequestProperty（Content-Type，contentType）; 
 connection.setRequestMethod（GET）; 
 connection.setDoOutput（false）; 
 int status = connection.getResponseCode（）; //返回200 
  

解决方案

在写入流并关闭流（ writer.write（）和 os.close（））之前调用（connection.getResponseCode（）） 这就是为什么服务器返回错误的请求代码（400）。
这是我现在可以使用的代码：

  / **创建连接** / 
 URL serverAddress =新的URL（uri）; 
 HttpURLConnection连接=（HttpURLConnection）serverAddress.openConnection（）; 
 connection.setDoOutput（true）; 
 connection.setDoInput（true）; 
 connection.setRequestProperty（Content-Type，contentType）; 
 connection.setRequestMethod（POST）; 
 
 / ** POSTing ** / 
 OutputStream os = connection.getOutputStream（）; 
 BufferedWriter writer = new BufferedWriter（new OutputStreamWriter（os，UTF-8））; 
 writer.write（getQuery（））; 
 writer.flush（）; 
 writer.close（）; 
 os.close（）; 
 connection.connect（）; 
 
 int status = connection.getResponseCode（）; //在执行HTTP POST时数据流准备就绪之前，无法调用
 PrinterClass.show（status）; （！状态= 200）//状态
如果
掷（新RESTfulWebServiceException（ 无效的HTTP响应状态 
 + 代码 +状态+ 从Web服务的服务器。））; 
 
 private String getQuery（）throws UnsupportedEncodingException 
 {
 JSONObject jobj = new JSONObject（）; 
 jobj.put（customerNumber，新的JSONString（003））; 
 jobj.put（mappingCode，new JSONString（jac_003））; 
 jobj.put（name，新的JSONString（johnny））; 
 jobj.put（status，新的JSONString（ACTIVE））; 
 PrinterClass.show（jobj.toString（））; 
 return jobj.toString（）; 
} 
  

Why server returns response code 400(bad request)? (doesn't work)

URL serverAddress = new URL(uri);
HttpURLConnection connection = (HttpURLConnection) serverAddress.openConnection();
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setRequestProperty("Content-Type", contentType);
connection.setRequestMethod("POST");
int status = connection.getResponseCode(); // returns 400

For example this HTTP GET returns code 200: (works)

/** Creating Connection **/
 URL serverAddress = new URL(uri);
 HttpURLConnection connection = (HttpURLConnection) serverAddress.openConnection();
 connection.setRequestProperty("Content-Type", contentType);
 connection.setRequestMethod("GET");
 connection.setDoOutput(false);
 int status = connection.getResponseCode(); // returns 200

解决方案

I've tried to get response code ( connection.getResponseCode() ) before I did actually wrote to a stream and close the stream ( writer.write() and os.close() ) thats why server returned Bad Request code(400). This is my code which works now:

            /** Creating Connection **/
            URL serverAddress = new URL(uri);
            HttpURLConnection connection = (HttpURLConnection) serverAddress.openConnection();
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setRequestProperty("Content-Type", contentType);
            connection.setRequestMethod("POST");

            /** POSTing **/
            OutputStream os = connection.getOutputStream();
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
            writer.write(getQuery());
            writer.flush();
            writer.close();
            os.close();
            connection.connect();

            int status = connection.getResponseCode();//this cannot be invoked before data stream is ready when performing HTTP POST
            PrinterClass.show(status);  //status
            if (status != 200)
                throw (new RESTfulWebServiceException("Invalid HTTP response status "
                    + "code " + status + " from web service server."));

private String getQuery() throws UnsupportedEncodingException
    {
        JSONObject jobj = new JSONObject();
        jobj.put("customerNumber", new JSONString("003"));
        jobj.put("mappingCode", new JSONString("jac_003"));
        jobj.put("name", new JSONString("johnny"));
        jobj.put("status", new JSONString("ACTIVE"));
        PrinterClass.show(jobj.toString());
        return jobj.toString();
    }

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